1) Field of the Invention
This invention relates to an input distribution type packet switch network and an input distribution type packet switch, more particularly an input distribution type packet switch network and an input distribution type packet switch which are preferably usable for large capacity-high speed digital communications, etc.
2) Description of the Prior Art
A circuit exchanging system and a packet-switching exchanging system are proposed and practically used as communication techniques to develop high speed digital communications.
In the circuit exchanging system, constant bit role line is provided to terminals to correspond to the request of the terminals. That is, a given digital signal is time division-multiplexed by bite unit, and time slots in a frame are recorded in a data buffer memory and read out in accordance with the predetermined order. In communication, since the time slots are read out in accordance with the predetermined order, the circuit exchanging system is suitable for a long time-communication at a constant speed.
On the other hand, in packet-switching exchanging system, a given digital signal is divided into packets having suitable size. Then, controlling information, such as an address, is added to the header of each packet, and the given digital signal is transmitted based on the controlling information. The size (length) of the packet is variable depending on the nature of the data. Therefore, the packet-switching exchanging system can have more communication patterns than the circuit exchanging system.
In the switching of the packet in the packet-switching exchanging system, a packet to be applied is divided into ATM cells, applied into a multistage connecting switch network, and is fabricated again into the packet in output. In this case, since reassembled traffic to be applied may be concentrated at some input ports and its nature has difficulty in being predicted, a Tandem Banyan switch or a MS4 switch is employed as a re-routing type multistage connecting switch network.
In the Banyan switch, if misrouting of a cell occurs in a Banyan switch network, the re-routing is not started until the cell is input into the next stage-Banyan switch network. As a result, misrouted cells cause the increase of the packet loss. Particularly, if a large traffic is input, the Banyan switch near the input side tends to have substantial misrouting and thus, have substantial packet loss.
On the other hand, in the MS4 switch, if misrouting of a cell occurs, the re-routing is started in the next stage switch element in the same switch network. Therefore, since the MS4 switch has a higher utilization efficiency of switch element and shorter time in re-routing than the Banyan switch, it can have relatively less packet loss.
However, since all of the cells are input from the left side of the MS4 switch network, if a large traffic is input into the MS4 switch network in high load, the misroute is apt to occur. Therefore, in this case, even the MS4 switch has relatively much packet loss.
It is an object of the present invention to provide a packet switch network and a packet switch which can reduce packet loss rate through the repressing of probability of misroute.
To achieve the object, this invention is directed to an input distribution packet switch network comprising a plurality of 2xc3x972 switch elements and packet input modules for the switch network. The switch elements are arranged in multistage and connected in accordance with Shuffle type topology and they constitute a Nxc3x97N switch network (N=2k, k: integral number of 2 and over), the links of the leftmost and rightmost switch elements being connected one another so that the Nxc3x97N switch network can have a ring architecture, the packet input modules being distributed laterally in the switch network.
Being different from the conventional re-routing type multistage connecting switch network, the packet can be directly applied into the switch network without the division for ATM cells, so that the switching throughput can be largely reduced.
Moreover, the packet input modules are placed and distributed laterally in the switch network. Therefore, if a large traffic is applied, each switch element in the switch network can have relatively small load because the packet input modules are distributed. Then, since the collision between the packets can be repressed, probability of misroute of the packet can be reduced. Consequently, the re-routing of the packet can be repressed and thus, packet loss rate can be reduced.
Furthermore, the switch elements constituting the switch network are connected in a ring architecture. Therefore, if the packet is applied from the rear packet input module of the switch network, it is transmitted to the leftmost switch element from the rightmost switch element in the switch network. Therefore, number of stages in the network is enough to switch the input packet network is.
Moreover, in the input distribution type packet switch network of the present invention, since the backward and frontward switch elements are effectively used through the transmission therebetween, the utilization efficiency of the switch elements can be enhanced. Therefore, the number of the switch elements constituting the switch network can be decreased.
Moreover, an input distribution type packet switch of the present invention has a first header processing part and a second header processing part. As described later, these header processing components are composed so as to be used as a practical switch through the addition of a switching header to applied packets.